基于改进遗传算法的电力系统无功优化

在简单遗传算法的基础上，针对无功优化的动态、多目标、多约柬以及非线性特点，提出了基于简单遗传算法的改进算法．改进遗传算法中采用了个体适应度函数的线性变换、归一化的选择方法，以及定向变异策略的应用．以Ward＆Hale6节点标准测试系统为例对该算法进行了有效性验证．仿真结果表明，该方法对电力系统的无功优化效果良好．     

A Probabilistic Methodology for the Assessment of Safety from Dropped Loads in Offshore Engineering

Pipeline damage by dropped objects from crane activities is a significant hazard for offshore platform installations. In this paper a probabilistic methodology is utilized for the estimation of the pipeline impact and rupture frequencies; this information is obtained both for the overall pipeline section exposed to the hazard and for a number of critical locations along the pipeline route. The presented algorithm has been implemented in a computer program that allows the analysis of a large number of possible drop points and pipeline target point locations. This methodology may be used in common risk analysis studies for evaluating the risk for platform personnel from dropped objects; however, the proposed technique may also be useful for other applications where engineering judgment has so far been the main driving criterion. In particular, two sample cases have been analyzed. The first one is the problem of selecting the best approaching route to a platform. By analyzing different route alternatives, a reduction of the impact frequency and therefore of the risk for the platform personnel may be achieved. The second application deals with the selection of the location for a safety valve at the riser base. The analysis may give useful information, such as the highest impact frequency location and the rupture frequencies upstream and downstream of the valve as a function of the valve position; this information, together with the transported medium inventory upstream of the valve, may give the designer a documented and justifiable rationale for selecting the best location for the valve from a safety point of view.     

Estimation of Correlation for Continuous Semimartingales

Abstract. In this study we are concerned with inference on the correlation parameter ρ of two Brownian motions, when only high‐frequency observations from two one‐dimensional continuous Itô semimartingales, driven by these particular Brownian motions, are available. Estimators for ρ are constructed in two situations: either when both components are observed (at the same time), or when only one component is observed and the other one represents its volatility process and thus has to be estimated from the data as well. In the first case it is shown that our estimator has the same asymptotic behaviour as the standard one for i.i.d. normal observations, whereas a feasible estimator can still be defined in the second framework, but with a slower rate of convergence.     

Affective and Cognitive Factors Influencing Sensitivity to Probabilistic Information

In study 1 different groups of female students were randomly assigned to one of four probabilistic information formats. Five different levels of probability of a genetic disease in an unborn child were presented to participants (within‐subject factor). After the presentation of the probability level, participants were requested to indicate the acceptable level of pain they would tolerate to avoid the disease (in their unborn child), their subjective evaluation of the disease risk, and their subjective evaluation of being worried by this risk. The results of study 1 confirmed the hypothesis that an experience‐based probability format decreases the subjective sense of worry about the disease, thus, presumably, weakening the tendency to overrate the probability of rare events. Study 2 showed that for the emotionally laden stimuli, the experience‐based probability format resulted in higher sensitivity to probability variations than other formats of probabilistic information. These advantages of the experience‐based probability format are interpreted in terms of two systems of information processing: the rational deliberative versus the affective experiential and the principle of stimulus‐response compatibility.     

步进电机的定位及速度控制软件设计

结合步进电机在数控系统中的应用，介绍８０３１ 单片机控制步进电机的方法及实现步进电机的精确定位、换向和速度控制的软件设计。     

一种分级超结构换热器网络综合优化方法及其应用

对分级超结构换热器网络模型的温度计算提出了一种通用的精确解方法,同时得到了显式解析解,并以这一解析解为基础,设计了以遗传算法和模拟退火算法为主,结合最速下降法的混合遗传算法,此外还在算法中引进精英策略和结构变异策略.应用实例的计算结果显示了这一混合遗传算法对于换热器网络的参数和结构都具有良好的搜索能力.     

宽带LFM信号去斜率数字脉压方法性能分析

在宽带LFM信号数字脉压中,去斜率数字脉压方法能有效地降低采样率,但是受到目标回波信号与参考信号的时延差的限制,只能作局部脉压处理。同时目标回波信号与参考信号的时延差和目标多普勒频率的变化,对去斜率数字脉压结果有一定的影响。该文通过理论分析和较全面的仿真,定量地分析了去斜率数字脉压中目标回波信号与参考信号时延差和多普勒频率的变化对数字脉压性能的影响,为工程应用中合理选择信号带宽、采样率和目标回波信号的时延提供了参考。     

相控阵雷达低仰角目标DOA估计的算法

在相控阵雷达跟踪低仰角目标时,采用频率捷变技术可以有效地减小雷达回波中直射信号和反射信号的相关性,抑制多径效应对目标到达方向估计造成的影响,提高角度估计的精度和性能。再用修正的AR模型算法,不仅可以在此基础上进一步去掉这两种信号的相关性,而且能正确估计出目标和镜像的仰角。计算机仿真实验结果验证了频率捷变和修正AR模型算法理论的正确性,以及在与其他方法比较的情况下,两者结合在去相关性能上的优越性和工程实用性。     

空气弹簧隔振器的动力特性研究

研究了空气弹簧隔振器的力学模型,导出了固有频率的计算公式.通过实例分析了影响固有频率的各种因素.研究结果表明,约束角度、相对阻尼系数及容积比等影响固有频率值;提高约束角度、增大气室容积和降低相对阻尼系数,可以改善空气弹簧隔振器的性能.     

基于改进遗传算法的单级多项目无能力约束生产批量问题研究

通过对单级多项目无能力约束生产批量问题(SMULP)模型进行分析，得出了一些重要的结论．分析了基本遗传算法的缺陷及其产生的原因．对该问题在遗传算法的编码、适应度函数、选择复制操作、交叉方法、交叉概率、变异概率和终止条件等各个环节进行了改进．采用VB6．0对SMULP改进遗传算法编程实现，能很好地与ERP软件集成．并对SMULP改进遗传算法进行了性能分析．